[blam]

"People as separated as the Japanese Ainu and Basques may share common Mediterranean roots and have become separated as a result of the post-ice age climate change.

The Relationship Between The Basque And The Ainu

I believe it was the Ainu who migrated back to Europe.

[Cronos]

I've read some speculation that state that the BAsque, the Chechens, the Dravidians and the Ainu were all relted. But it seems mostly speculation to me as the distances and time spans are too great.